Former Gov. Arnold Schwarzenegger made a rare political appearance on Monday in Sacramento to promote California’s fight against climate change and to attend a ceremony to unveil his official portrait as governor.

The state Senate leader is proposing a tax on consumer fuel purchases of gasoline, oil, diesel, ethanol and natural gas, with the money raised diverted to transit projects and households of a certain income level.

California’s new system for limiting industrial greenhouse gas emissions by putting a price on carbon is not likely to spur a similar federal program anytime soon, but it might influence other states to follow suit.

California’s largest greenhouse gas emitters will begin buying permits in a landmark “cap-and-trade” system designed to control emissions of heat-trapping gases and to spur investment in clean technologies.

Dozens of people, some wearing red “Save Our Jobs” T-shirts, packed a public meeting on Thursday to testify that a key component of California’s landmark greenhouse gas emissions law will impose enormous costs on them and consumers.

California formally adopted the nation’s most comprehensive so-called “cap-and-trade” system Thursday, an experiment designed to provide financial incentives for polluters to reduce greenhouse gas emissions.